example-bot: Add note about encrypting for MUCs

Signed-off-by: Maxime “pep” Buquet <pep@bouah.net>

examples/echo_client.py

@@ -156,6 +156,12 @@ class EchoBot(ClientXMPP):
                 # `encrypt_message` excepts the plaintext to be sent, a list of
                 # bare JIDs to encrypt to, and optionally a dict of problems to
                 # expect per bare JID.
+                #
+                # Note that this function returns an `<encrypted/>` object,
+                # and not a full Message stanza. This combined with the
+                # `recipients` parameter that requires for a list of JIDs,
+                # allows you to encrypt for 1:1 as well as groupchats (MUC).
+                #
                 # TODO: Document expect_problems
                 recipients = [mto]
                 encrypt = await self['xep_0384'].encrypt_message(body, recipients)